The Tambourissa genus belongs to the Monimiaceae family and comprises about 43 species found throughout the western islands of the Indian Ocean, such as Madagascar, Comoros and the Mascarenes islands (Mauritius and Reunion). The various Tambourissa species tend to show endemic specificity as most of them are localized in only one island and in only one habitat.
Tambourissa trichophylla (Baker) growths in Madagascar and Comoros. It is a tree of from about 5 meters to about 12 meters high. The leaves are opposite, oblong to lanceolate, from 8 to 20 cm long, dentate on the upper part. Male flowers are 5-6 mm in diameter, axillaris or terminal, from 1.5 to 3 cm long. Fruits are globes, about 4 cm in diameter, with coriaceus pericarp and numerous drupes. In Madagascar, this plant is called Amborahasa or Ambora and is traditionally used in health care, for instance for scar improvement and keloids (bark) or oral care (tea leaves as mouthwash).
Other Tambourissa species are also used in traditional treatments: crushed fresh leaves of Tambourissa microphylla are directly applied onto the skin for wound healing action, Tambourissa religiosa is used for tissue repair and Tambourissa capuronii (leaves crushed with liquid vegetal waxes) helps for dandruff treatment.
Tambourissa trichophylla is known to contain polyphenols and flavonoids, including epicatechin, nicotiflorin and rutin (Thesis of A. Lhuillier, L'Iinstitut National Polytechnique de Toulouse, 2007).
Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol unit or building block per molecule. Polyphenols are generally classified as hydrolyzable tannins (gallic acid esters of glucose and other sugars) and phenylpropanoids, such as lignins, flavonoids, and condensed tannins. Polyphenols have been shown to have antioxidant characteristics with potential health benefits.
Flavonoids are widely distributed in plants and help plants carry out many functions including helping in the production of yellow or red/blue pigmentation in flowers and helping protect against attack by microbes and insects. Flavonoids have a widespread distribution in plants, come in a great variety and generally have low human toxicity. Flavonoids have been referred to as “nature's biological response modifiers” because of strong experimental evidence suggesting that flavonoids have an ability to modify the body's reaction to allergens, viruses, and carcinogens. Some flavenoids show anti-allergic, anti-inflammatory, anti-microbial and anti-cancer activity.
Rutin, also called rutoside, is a citrus flavonoid glycoside having a structure similar to the flavonol quercetin and the disaccharide rutinose. It can be found in Ruta graveolens, buckwheat, the leaves and petioles of Rheum species, as well as other sources.
Rutin can combine with cations: in humans, it attaches to iron ions, Fe+2, preventing iron from binding to hydrogen peroxide and from creating free-radical cellular damage. Rutin is also an antioxidant, and therefore can play a role in inhibiting some cancers. Rutin is also an anti-inflammatory agent. Rutin strengthens blood vessels, decreases the permeability of cell walls and acts as a vasodilatator. It can also act on edema in blood vessels and so decrease thrombosis risk. Rutin can help to decrease the cytoxicity of oxygenated DTL cholesterol, which may be one of the factors responsible for the development of atherosclerosis.

Epicatechin is also a flavonoid and is a major polyphenolic component of green tea (Camellia sinensis) and may also be found in other species. Epicatechin has been shown to be an anti-oxidant, to improve cardiovascular function, to increase blood flow in the brain and to be active against hepatotropic viruses.

Nicotiflorin is a flavonoid glycoside that can be found as such or as kaempferol-3-O-rutinoside glycosides in almonds (Prunus dulcis), green tea (Camellia sinensis), Carthamus tinctorius, Pogonatherum crinitum, Centaurea hierapolitana, Microcos paniculata, etc. Research on this compound has shown interesting properties with respect to its anti-oxidant potential, activity on blood circulation improvement. It is also a fibroblast growth promoter or can participate to anti-itching or to sunscreen activity. A composition containing nicotiflorin is claimed for wrinkles prevention by inducing collagen synthesis and inhibiting collagenase.

Antimicrobial peptides or proteins (or AMPs, also called host defense peptides) are broad-spectrum antibiomicrobial compounds and correspond to one of the primary mechanisms used by the multiple epithelial surfaces (more specifically skin) in the early stages of immune defense. AMPs include α- or β-defensin, RNase-7, S100-protein psoriasin or cathelicidin LL-37. The antimicrobial activity deals with Gram positive and Gram negative bacteria but also with fungi and viruses. The production of antimicrobial peptides or proteins by human skin occurs constitutively but seems also modulated after infection, inflammation or injury. Some skin diseases show altered expression of AMPs. For example their levels are increased in psoriatic lesions and decreased for atopic lesions (atopic dermatitis patients).
Cathelicidin is a cationic antimicrobial peptide expressed in most of the circulating immune cells (monocytes, leukocytes, neurophils etc) and also in epidermal keratinocytes. Cathelicidin is produced in various epithelia like skin or mucous membranes but also in sweat glands and sebocytes of the skin or scalp. hCAP18—human Cathelicidin Anti-Microbial Peptide of 18 kDa—comprises a cathelin-like domain and a C-terminal peptide called LL-37 (a peptide beginning with 2 leucine residues that is 37 amino acids long). The activity of cathelicidin is controlled by enzymatic processing of the proform (hCAP18) to a mature peptide (LL-37), which is induced by a proteolytic process involving kallikreins (such as Stratum corneum tryptic enzyme also called SCTE or kallikrein-5, S Stratum corneum chemotryptic enzyme also called SCCE or kallikrein-7).
In healthy skin, epidermal keratinocytes express low amounts of cathelicidin. On infection or barrier disruption, cathelicidin is strongly induced and is either released by neutrophils or may be stored by keratinocytes in lamellar bodies. In case of wound healing, cathelicidin participates of course to microbial defense but also to the skin repair process as it activates pro-inflammatory cytokines synthesis, chemotaxis of immune cells, angiogenesis and proteoglycan expression. In rosacea, increased cathelicidin expression in the LL-37 peptide form has been observed—along with kallikreins activity activation. Abnormal AMP expression also exists in psoriasis as cathelicidin has been shown to be increased in psoriatic lesional skin.
U.S. Pat. No. 7,718,618 to Gallo et al., issued May 18, 2010, discloses the use of cathelicidin or related synthetic peptides for anti-microbial activity, U.S. Pat. No. 7,777,000 to Gallo et al., issued Aug. 17, 2010, describes anti-viral activity and such in dermatitis, PCT Patent Publication No. WO 2004/067025 (also published as U.S. Pat. No. 7,452,864 to Ståle-Bächdal, issued Nov. 18, 2008) discloses its use in wound healing by causing cell proliferation and regeneration. European Patent Application No. 1,358,888 (also published as U.S. Publication Number 2006/0275303) discloses its use in angiogenesis induction. U.S. Publication No. 2008/0038374 describes the upregulation of cathelicidin and the subsequent effect on diseases, for example with Vitamin D and via sphingosylphosphoryl choline. PCT Patent Publication No. WO 2008/060362 (also published as U.S. Publication No. 2009/0318534) describes cathelicidin inhibitors—comprising antisense or ribozyme molecule or a vitamin D3 antagonist—and their use in rosacea and acne. The disadvantage of the use of these inhibitors, however, is that antisense oligonucleotides and ribozyme molecules are not readily available and many vitamin D antagonists, such as e.g. cortisone, have severe side effects.
Rosacea is a chronic inflammatory disease, generally occurring on the face, which affects about 45 millions people worldwide. It corresponds to vascular disorder and is characterized by telangiectasia (visible hemorrhagic dilated blood capillaries near the skin surface), erythema, papules, and pustules primary in the central areas of the face combined with frequent burning and itching sensations. Rosacea affects mostly Caucasians of mainly northwestern European descent, and concerns both sexes, but is almost three times more common in women, and has a peak age of onset between 30 and 60.
The existing rosacea therapeutics, which may be administered topically or administered systemically, include antibiotics, such as tetracycline, minocycline, erythromycin and doxycyline, azetromycin; anti-infectives, like azelaic acid, nadifloxacin, sodium sulfacetamide and metronidazole; anti-inflammatories with folic acids, nicotinamide and zinc oxide; Keratolysis activators, for example benzoyl peroxide, resorcinol and salicylic acid; and retinoids. These compounds and their formulations, however, are not always in rosacea and acne treatment.
Topical applications of metronidazole—cream or lotion with 0.75% to 1% active compound—are the most frequent treatment and have been shown to be effective when applied once or twice daily for 8-12 weeks. Some side effects related with use of metronidazole, including dry skin, skin redness or irritation, may occur.
Rosacea has multiple origins and may have causes like heredity, neurological disorders, gastric issues and other causes. Main causes that can be alleviated by topical treatment include: (a) an over-expression of active forms of antimicrobial peptides (cathelicidins) and related enzymes, involved in the maintenance of an infectious status leading to skin chronic inflammation or being favorable to skin inflammation chronicity; (b) a vascular defect, which contributes to impaired capillary neoangiogenesis with frequent hemorrhagic characteristics, leading to the weakening of a skin that naturally tends to be thin and reactive; (c) inflammation, initially elusive but steadily increasing to become persistent with flush and blush phenomena; and (d) an inflammatory process depending to environmental conditions such as UVs or free radicals.